In prosthetics, an amputee normally dons a prosthetic device by inserting his/her residual limb into a socket portion of the prosthesis. It is now fairly typical for an amputee to first place a prosthetic liner over the residual limb prior to insertion of the residual limb into the prosthetic socket, the prosthetic liner acting at least as a cushioning interface between the limb and socket. The Alpha® Liner series of prosthetic liners from the Ohio Willow Wood Company in Mt. Sterling, Ohio has proven to be quite popular for this purpose.
Regardless of the selected limb preparation, the prosthesis must be securely retained on the residual limb in order to permit proper prosthesis function and amputee comfort. Various techniques for prosthesis retention (suspension) have been utilized over the years, and these techniques would be well known to one of skill in the art. Two suspension techniques that have become increasingly popular—especially since the advent of modem prosthetic liners—are locking (e.g., pin lock) suspension and vacuum (suction) suspension.
In the case of locking suspension, a pin or similar element is typically secured to the distal end of a prosthetic liner and a corresponding pin-receiving lock element is located in a distal end of a prosthetic socket. Upon insertion of the liner-covered residual limb into the socket, engagement of the pin and lock element serves to retain the associated prosthesis on the residual limb. In the case of vacuum suspension, a typically liner-covered residual limb is inserted into a prosthetic socket. A suspension sleeve may also be placed over the brim portion of the socket so as to overlie both the socket exterior and a portion of the residual limb (or liner). In this manner, air may be prevented from entering or exiting the socket from the proximal end thereof, thereby facilitating the creation and maintenance of a vacuum within the socket. A vacuum device can then be used to evacuate the socket interior to some desired vacuum level, the force of the vacuum holding the prosthetic socket (and prosthesis) on the residual limb.
Obviously, the ability to generate and maintain a vacuum is critical in the case of prosthetic vacuum suspension. If an adequate vacuum level cannot be produced within the socket, the associated prosthesis will not be properly secured to the residual limb. If vacuum is lost during use of the prosthesis, the prosthesis may become loose leading to possible discomfort or malfunction. Adequately sealing a prosthetic socket can be difficult even in the case of a below-knee, i.e., trans-tibial, (TT) amputee. However, these difficulties are often compounded in the case of an above-knee, i.e., trans-femoral (TF) amputee.
More specifically, while there are known and effective vacuum suspension solutions for TT amputees, no similarly effective vacuum solutions have been developed for TF amputees. Rather, the most common TT socket sealing solution is to place a suspension (sealing) sleeve over the outside of the socket and the liner covering the wearer's thigh. However, since TF sockets do not have sufficient room above the brim of the socket for sealing to the liner, the liner must be reflected over the brim of the socket and then sealed to the socket with a sleeve. This technique is not very durable because amputees commonly bump the brim of the socket against hard objects, which may damage the liner and/or the sleeve. Furthermore, the presence of a bulky sealing sleeve near or in the groin area may be quite uncomfortable to an amputee.
Internal sealing systems have been developed for TF prostheses, but all known systems have unacceptable drawbacks. These drawbacks include, without limitation: that the seal requires an intimate fit to the residual limb and will not be effective if the limb shrinks or moves in such a way as to break the seal; that the seal resides too low within the socket, and resulting vacuum suspension is thereby concentrated over too small of an area of the residual limb; and that the sealing element is too restrictive and must be fit very carefully to avoid a constricting “tourniquet effect” on the residual limb.
Therefore, it can be understood from the foregoing discussion that there is a need for an improved vacuum suspension sealing system, especially an improved vacuum suspension sealing system for a TF prosthesis. Sealing systems and methods of the present invention satisfy these needs.